KR100845134B1 - Digitally self-calibrating pipeline analog-to-digital converter and method of calibrating the same - Google Patents

Abstract

A pipelined analog-to-digital converter having an automatic correction circuit and a digital correction method thereof are disclosed. The pipeline analog-to-digital converter includes a pipeline conversion circuit and a digital correction circuit. The pipeline conversion circuit has a plurality of cascaded one bit stages and converts an analog input signal into a first digital signal having a plurality of bits. The digital correction circuit receives the first digital signal from the pipeline conversion circuit, extracts and stores a correction coefficient for each of the plurality of 1-bit stages, reads the correction coefficient and corrects the feedback signal to correct the second digital signal having a plurality of bits. Generates. Thus, the pipelined analog-to-digital converter has an automatic digital correction function and is excellent in linearity.

Description

PIPELINE ANALOG-TO-DIGITAL CONVERTER AND METHOD OF CALIBRATING THE SAME}

1A is a graph showing the transfer characteristics of an ideal pipeline analog-to-digital converter.

1B is a graph showing the transfer characteristics of an actual pipeline analog-to-digital converter.

2A and 2B are conceptual views illustrating the concept of a calibration method of a pipelined analog-to-digital converter according to the present invention.

3 and 4 are algorithms illustrating a method of correcting a pipelined analog-to-digital converter according to an embodiment of the present invention.

5 is a block diagram illustrating a pipelined analog-to-digital converter according to one embodiment of the present invention.

FIG. 6 is a circuit diagram illustrating a configuration of stages of a pipeline conversion circuit in the pipeline analog-to-digital converter of FIG. 5.

FIG. 7 is a conceptual diagram illustrating an architecture of the pipelined analog-to-digital converter of FIG. 5.

FIG. 8 is a block diagram illustrating a digital correction circuit included in the pipelined analog-to-digital converter of FIG. 5.

FIG. 9 is a circuit diagram illustrating a basic digital correction circuit included in the digital correction circuit of FIG. 8.

FIG. 10 is a block diagram illustrating a correction control circuit included in the digital correction circuit of FIG. 8.

FIG. 11 is a block diagram illustrating a clock generator included in the correction control circuit of FIG. 10.

FIG. 12 is a block diagram illustrating a flag generator included in the correction control circuit of FIG. 10.

FIG. 13 is a circuit diagram illustrating a correction control signal generator included in the correction control circuit of FIG. 10.

FIG. 14 is a circuit diagram illustrating a part of a correction coefficient extraction circuit included in the digital correction circuit of FIG. 8.

FIG. 15 is a circuit diagram illustrating a control signal generator for generating control signals in the correction coefficient extraction circuit of FIG. 14.

FIG. 16 is a timing diagram illustrating an operation of the control signal generator illustrated in FIG. 15.

FIG. 17 is a block diagram illustrating a correction output circuit included in the digital correction circuit of FIG. 8.

18 is a block diagram illustrating an adder included in the digital correction circuit of FIG. 8.

19 is a timing diagram illustrating an operation of the digital correction circuit of FIG. 8.

20A and 20B are simulations showing the operation of the pipelined analog-to-digital converter according to the embodiment of the present invention shown in FIG.

Explanation of symbols on the main parts of the drawings

1000: pipeline analog-to-digital converter

1100: pipeline conversion circuit

1300: digital correction circuit

1310: basic digital correction circuit

1320: correction control circuit

1330: correction coefficient extraction circuit

1340: correction output circuit

1360: adder

The present invention relates to a pipelined analog-to-digital converter, and more particularly to a pipelined analog-to-digital converter having a digital correction function and a digital correction method of the pipelined analog-to-digital converter.

Analog-to-Digital Converters (ADCs) are used to quantize electrical signals used in digital signal processing. Two parameters that determine the performance of an ADC are resolution and sampling rate. The resolution indicates how small the voltage or current the ADC can resolve, and the sampling rate indicates how quickly the ADC can quantize electrical signals into digital output data.

To improve the performance of a system using an ADC, a high resolution ADC that operates at high speed is required. In addition, sophisticated digital signal processing requires a high performance ADC. In the past, high-performance, high-speed ADCs were implemented using expensive hybrid devices or discrete devices, making it difficult to reduce manufacturing costs. Therefore, MOS (Metal Oxide Semiconductor) integrated circuit (IC) process was required to manufacture high-performance ADC at low cost.

However, due to process limitations, mismatching may occur between MOS devices.

Thus, in order to implement an ADC having a high resolution of 14 bits or more, a calibration technique for detecting and eliminating error components due to process mismatches and finite device characteristics is required.

It is an object of the present invention to provide a pipelined analog-to-digital converter having a digital correction circuit which can be incorporated into the analog-to-digital converter.

Another object of the present invention is to provide a digital correction method of a pipelined analog-to-digital converter having a digital correction circuit that can be embedded in the analog-to-digital converter.

In order to achieve the above object, a pipeline analog-to-digital converter according to one embodiment of the present invention includes a pipeline conversion circuit and a digital correction circuit.

The pipeline conversion circuit has a plurality of cascaded one bit stages and converts an analog input signal into a first digital signal having a plurality of bits. The digital correction circuit extracts a correction coefficient for each bit of the first digital signal based on a correction control signal and a feedback converter output signal, and corrects the first digital signal in response to the correction coefficient to have a plurality of bits. Generate a second digital signal.

According to one embodiment of the invention, the digital correction circuit comprises a basic digital correction circuit, a correction control circuit, a correction coefficient extraction circuit, a correction output circuit and an adder.

A basic digital correction circuit performs a basic correction on the first digital signal and generates a third digital signal. The correction control circuit generates a reference clock signal, a first correction control signal having a plurality of bits, and a second correction control signal having a plurality of bits in response to the first clock signal and the first flag signal. The correction coefficient extracting circuit extracts a plurality of first correction coefficients for the first digital signal in response to the reference clock signal, the first correction control signal, the second correction control signal, and the feedback signal. A correction output circuit generates a second correction coefficient having a plurality of bits based on each bit of the first digital signal and the plurality of first correction coefficients. An adder adds the second correction coefficient to the third digital signal to generate the second digital signal.

A digital correction method of an analog-to-digital converter according to an embodiment of the present invention includes the steps of performing a basic correction on a first digital signal and generating a third digital signal; Generating a reference clock signal, a first correction control signal having a plurality of bits, and a second correction control signal having a plurality of bits in response to the first clock signal and the first flag signal; Extracting a plurality of first correction coefficients for the first digital signal in response to the reference clock signal, the first correction control signal, the second correction control signal, and the feedback signal; Generating a second correction coefficient having a plurality of bits based on each bit of the first digital signal and the plurality of first correction coefficients; And generating the second digital signal by adding the second correction coefficient to the third digital signal.

With respect to the embodiments of the present invention disclosed in the text, specific structural to functional descriptions are merely illustrated for the purpose of describing embodiments of the present invention, embodiments of the present invention may be implemented in various forms and It should not be construed as limited to the embodiments described in.

As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between. Other expressions describing the relationship between components, such as "between" and "immediately between," or "neighboring to," and "directly neighboring to" should be interpreted as well.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof that is described, and that one or more other features or numbers are present. It should be understood that it does not exclude in advance the possibility of the presence or addition of steps, actions, components, parts or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

On the other hand, when an embodiment is otherwise implemented, a function or operation specified in a specific block may occur out of the order specified in the flowchart. For example, two consecutive blocks may actually be performed substantially simultaneously, and the blocks may be performed upside down depending on the function or operation involved.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1A is a graph showing the transfer characteristics of an ideal pipeline analog-to-digital converter, and FIG. 1B is a graph showing the transfer characteristics of an actual pipeline analog-to-digital converter. 1A and 1B, VI represents an input voltage, VO represents an output voltage, and VREF represents a reference voltage.

Referring to FIG. 1A, in the ideal case, the curve representing data “0” (D = 0) has an output voltage VO of + VREF when the input voltage VI is 0V, and the data “1” (D = In the curve 1), when the input voltage VI is 0V, the output voltage VO has a value of -VREF. Referring to FIG. 1B, in the actual case, the curve representing the data "0" (D = 0) has an output voltage VO having a value of S1 rather than + VREF when the input voltage VI is 0V, and the data "1". The curve representing "(D = 1) has an output voltage VO of S2 instead of -VREF when the input voltage VI is 0V. The difference between S1 and + VREF and the difference between S2 and -VREF correspond to an error. This error may be due to inconsistencies in the MOS process, which is a semiconductor manufacturing process, and finite device characteristics. In these ideal and practical cases, the linearity of the ADC can be reduced due to differences in the transfer characteristics of pipelined analog-to-digital converters.

2A and 2B are conceptual views illustrating a concept of a digital data correction method of a pipelined analog-to-digital converter according to the present invention.

2A and 2B, a digital data correction method of a pipelined analog-to-digital converter includes an extract / store mode and a read / correct mode. As shown in Fig. 1B, S1 represents the value of the output voltage VO at the point where the curve representing data "0" (D = 0) meets the vertical axis, and S2 represents data "1" (D = 1). The value of the output voltage VO is shown at the point where the curves meet the vertical axis.

Referring to FIG. 2A, the following operation is performed in the extraction / storage mode.

1) Obtain S2.

2) Obtain S1.

3) Find (S2-S1) / 2 and call this value IC.

Referring to FIG. 2B, the following operation is performed in the read / modify mode.

1) Data D is obtained.

2) If the value of D is "0", the IC value is added to the output data DO.

3) If the value of D is "1", the IC value is subtracted from the output data D0.

The correction of the pipeline analog-to-digital converter is performed in response to the flag signal.

3 and 4 are algorithms illustrating a method of correcting a pipelined analog-to-digital converter according to an embodiment of the present invention. 3 shows the calibration algorithm of the ADC in the extraction / storage mode, and FIG. 4 shows the calibration algorithm of the ADC in the read / correction mode. 3 and 4, last_stg represents the final stage.

Referring to FIG. 3, the calibration algorithm of the ADC in the extraction / storage mode is as follows.

1) The flag signal CFLAG is detected (S11).

2) It is determined whether CFLAG = 1, and if CFLAG = 1, CFLAG is detected again (S12).

3) If CFLAG = 1, the last stage is set to n (S13).

4) Let Dn = 1 and Vin = CML for stage n (S14). Here, CML means an intermediate value (S14).

5) The output data D0 is read (S15).

6) ICn = ICn + DO is performed (S16).

7) It is determined whether t> = 2048 (S17).

8) If t> = 2048, t = t + 1 is performed and the process proceeds to S15 (S18).

9) If t> = 2048, Dn = 0 and Vin = CML for stage n are set (S19).

10) Read the output data D0 (S20).

11) ICn = ICn-DO is performed (S21).

12) It is determined whether u> = 2048 (S22).

13) If u> = 2048, u = u + 1 is performed and the process goes to S20 (S23).

14) If u> = 2048, ICn = ICn / (2048 × 2) is performed (S24).

15) It is determined whether n = 1 (S25).

16) If n = 1, perform n = n-1 and go to S13 (S26).

17) If n = 1, IC1 to IClast_stg are stored (S27).

Referring to FIG. 4, the calibration algorithm of the ADC in the read / modify mode is as follows.

1) It is checked whether n = 1 (S28).

2) The input data Dn is read (S29).

3) It is determined whether Dn = 1 (S30).

4) If Dn = 1, the ICn value is read (S31), and ICT = ICT + ICn (S33).

5) If Dn = 1, the ICn value is read (S32), and ICT = ICT-ICn is performed (S34).

6) It is determined whether n> = last_stg (S35).

7) If n> = last_stg, perform n = n + 1 and go to S29 (S36).

8) If n> = last_stg, DO = DO + ICT is performed (S37).

9) Truncation of the least significant two bits (S38).

10) Determine whether it is the last operation, and if not, go to S28 (S39).

11) If it is the last operation, the operation ends.

5 is a block diagram illustrating a pipelined analog-to-digital converter according to one embodiment of the present invention.

Referring to FIG. 5, the pipeline analog-to-digital converter 1000 includes a pipeline conversion circuit 1100 and a digital correction circuit 1300.

The pipeline conversion circuit 1100 has cascaded 1-bit stages 1110, 1120, and 1130, and converts the analog input signal VIN into first digital signals D1 to Dn having a plurality of bits. The digital correction circuit 1300 receives the first digital signals D1 to Dn from the pipeline conversion circuit 1100. The digital correction circuit 1300 extracts a correction coefficient for each of the plurality of 1-bit stages, corrects the feedback signal based on the correction coefficient and the first digital control signal, and generates a second digital signal CDO having a plurality of bits. Generate.

Referring to FIG. 5, the output signal VO1 of the first stage 1110 becomes the input signal VI2 of the second stage 1120, and the output signal of the n−1th stage 1130 is the nth stage ( The input signal VIN of 1130 is obtained.

FIG. 6 is a circuit diagram illustrating a configuration of stages of a pipeline conversion circuit in the pipeline analog-to-digital converter of FIG. 5.

Referring to FIG. 6, the first stage 1110 of the pipeline conversion circuit 1100 includes a first amplifier 1111, a first comparator 1112, a first selection circuit 1114, and a first adder 1113. It includes.

The first amplifier 1111 amplifies the analog input signal VIN using gain 2. The first comparator 1112 compares the analog input signal VIN with a ground voltage. The output signal of the first comparator 1112 becomes the first bit D1 of the first digital signals D1 to Dn. The first selection circuit 1114 may be configured as a switch and operates in response to the first bit D1 of the first digital signals D1 to Dn. The first selection circuit 1114 selects -VREF when the first bit D1 of the first digital signals D1 to Dn is logic "1", and selects the first bit of the second digital signal D1 to Dn. If (D1) is logic "0", select + VREF. The first adder 1113 adds the output signal of the first selection circuit 1114 to the output signal of the first amplifier 1111.

The second stage 1120 of the pipeline conversion circuit 1100 includes a second amplifier 1121, a second comparator 1122, a second selection circuit 1124, and a second adder 1123.

The second amplifier 1121 amplifies the output signal VI2 of the first stage 1110 of the pipeline conversion circuit 1100 using the gain 2. The second comparator 1122 compares the output signal VI2 of the first stage 1110 with the ground voltage. The output signal of the second comparator 1122 becomes the second bit D2 of the first digital signals D1 to Dn. The second selection circuit 1124 may be configured as a switch and operates in response to the second bit D2 of the first digital signals D1 to Dn. The second selection circuit 1124 selects and outputs -VREF when the second bit D2 of the first digital signals D1 to Dn is logic " 1 ", and selects the second signal of the second digital signals D1 to Dn. If two bits D2 are logic "0", + VREF is selected and output. The second adder 1123 adds the output signal of the second selection circuit 1124 to the output signal of the second amplifier 1121 to generate the output signal VO2 of the second stage 1120.

FIG. 7 is a conceptual diagram illustrating an architecture of the pipelined analog-to-digital converter of FIG. 5. In FIG. 7, the amplifiers included in the fourth stage, the ninth stage, and the fourteenth stage are amplifiers having a gain of 1. The architecture of the pipelined analog-to-digital converter of FIG. 7 includes 19 1 bit stages (Stage 1 to Stage 19), but the output data bits (OUTPUT BITS) are 14 bits. Stage 4 and stage 5 overlap, stage 9 and stage 10 overlap, and stage 14 and stage 15 are designed to overlap.

The architecture of the pipelined analog-to-digital converter shown in FIG. 7 is designed to calibrate 13 stages from stage 1 to stage 13 in full calibration mode, and the calibrated stages are selected by an external control signal. Because digital correction changes analog error values to digital values, truncation errors can occur in binary operations. To keep this truncation error below 1/4 LSB, two 1 bit stages (stage 18 and stage 19) are added.

FIG. 8 is a block diagram illustrating a digital correction circuit 1300 included in the pipelined analog-to-digital converter 1000 of FIG. 5.

Referring to FIG. 8, the digital correction circuit 1300 includes a basic digital correction circuit 1310, a correction control circuit 1320, a correction coefficient extraction circuit 1330, a correction output circuit 1340, and an adder 1360. do.

The basic digital correction circuit 1310 performs basic correction on the first digital signals D1 to Dn and generates a third digital signal RDO. The correction control circuit 1320 may include a reference clock signal RCLK, a first correction control signal C having a plurality of bits, and a plurality of bits in response to the first clock signal CKIN and the first flag signal CFLAG. Generate a second correction control signal (S) having a. The correction coefficient extracting circuit 1330 is configured to generate the first digital signals D1 to Dn in response to the reference clock signal RCLK, the first correction control signal C, the second correction control signal S, and the feedback signal. A plurality of first correction coefficients IC1 to IC13 are extracted. The correction output circuit 1340 generates a second correction coefficient ICT having a plurality of bits based on each bit of the first digital signals D1 to Dn and the plurality of first correction coefficients IC1 to IC13. The adder 1360 generates the second digital signal CDO by adding the second correction coefficient ICT to the third digital signal RDO.

FIG. 9 is a circuit diagram illustrating a basic digital correction circuit 1310 included in the digital correction circuit 1300 of FIG. 8.

Referring to FIG. 9, the basic digital correction circuit 1310 includes flip-flop arrays for delaying each bit of the first digital signals D1 to Dn in response to the clock signal CK and the inverted clock signal CKB. have. The first flip-flop array includes flip-flops F1, F2, F3, F4, and F5, and includes a first flip-flop array. The first flip-flop array includes first flip-flops F1, F2, F3, F4, and F5. Delay one bit (D1). The second flip-flop array includes flip-flops F6, F7, F8, and F9, and the second bits of the first digital signals D1 to Dn in response to the clock signal CK and the inverted clock signal CKB. Delay (D2). The nineteenth flip-flop array includes a flip-flop F10 and delays the nineteenth bit D19 of the first digital signals D1 to Dn in response to the clock signal CK. The basic digital correction circuit 1310 outputs an output signal of 16 flip-flop arrays among the 19 flip-flop arrays as a third digital signal RDO.

FIG. 10 is a block diagram illustrating a correction control circuit 1320 included in the digital correction circuit 1300 of FIG. 8.

Referring to FIG. 10, the correction control circuit 1320 includes a clock generator 1321, a flag generator 1325, and a correction control signal generator 1333.

The clock generator 1321 divides the first clock signal CKIN to generate a second clock signal BCLK, a reference clock signal RCLK, and a third clock signal TCLK. The flag generator 1325 detects the first flag signal CFLAG in response to the second clock signal BCLK, the reference clock signal RCLK, and the third clock signal TCLK, and detects the second flag signal TFLAG. Generate. The correction control signal generator 1329 generates the first correction control signals C13 to C1 and the second correction control signals S13 to S1 in response to the third clock signal TCLK and the second flag signal TFLAG. .

FIG. 11 is a block diagram illustrating a clock generator 1321 included in the correction control circuit 1320 of FIG. 10.

Referring to FIG. 11, the clock generator 1321 includes a first clock divider 1322, a second clock divider 1323, and a third clock divider 1324.

The first clock divider 1322 divides the first clock signal CKIN at a division ratio of 1/64 to generate a second clock signal BCLK. The second clock divider 1323 divides the second clock signal BCLK at a division ratio of 1/33 to generate the reference clock signal RCLK. The third clock divider 1324 divides the reference clock signal RCLK at a dividing ratio of 1/2 to generate a third clock signal TCLK.

12 is a block diagram illustrating a flag generator 1325 included in the correction control circuit 1320 of FIG. 10.

12, the flag generator 1325 includes a first pulse detector 1326, a second pulse detector 1327, and a third pulse detector 1328.

The first pulse detector 1326 detects an edge of the first flag signal CFLAG in response to the second clock signal BCLK and generates a third flag signal BFLAG. The second pulse detector 1327 detects an edge of the third flag signal BFLAG in response to the reference clock signal RCLK and generates a fourth flag signal RFLAG. The third pulse detector 1328 detects an edge of the fourth flag signal RFLAG and generates a second flag signal TFLAG in response to the third clock signal TCLK.

FIG. 13 is a block diagram illustrating a correction control signal generator 1327 included in the correction control circuit 1320 of FIG. 10.

Referring to FIG. 13, the correction control signal generator 1329 includes an inverter INV1, flip-flops F11, F12, F13, F14, F15, F16, F17, and F18, and OR gates OR1, OR2, and OR3. ).

The inverter INV1 inverts the third clock signal TCLK. The output signal of the inverter INV1, that is, the inverted third clock signal, is applied to the flip-flops F11, F13, F15, and F17, and the third clock signal (F12, F14, F16, F18) is applied to the flip-flops F12, F13, F15, and F17. TCLK) is applied. The first flip-flop F11 detects an edge of the second flag signal TFLAG in response to the output signal of the inverter INV1. The second flip-flop F12 detects an edge of the output signal of the first flip-flop F11 in response to the third clock signal TCLK. The third flip-flop F13 detects an edge of the output signal of the second flip-flop F12 in response to the output signal of the inverter INV1. The fourth flip-flop F14 detects an edge of the output signal of the third flip-flop F13 in response to the third clock signal TCLK. The fifth flip-flop F15 detects an edge of the output signal of the fourth flip-flop F14 in response to the output signal of the inverter INV1. The sixth flip-flop F16 detects an edge of the output signal of the fifth flip-flop F15 in response to the third clock signal TCLK. The seventh flip-flop F17 detects an edge of the output signal of the sixth flip-flop F16 in response to the output signal of the inverter INV1. The eighth flip-flop F18 detects an edge of the output signal of the seventh flip-flop F17 in response to the third clock signal TCLK.

The first OR gate OR1 performs an OR operation on the output signal of the first flip-flop F11 and the output signal of the third flip-flop F13 and performs the twelfth bit of the second correction control signal S ( S12) is generated. The second OR gate OR2 performs an OR operation on the output signal of the first OR gate OR1 and the output signal of the fifth flip-flop F15, and executes the eleventh bit of the second correction control signal S ( S11) is generated. The sixth OR gate OR3 performs an OR operation on the output signal of the fifth OR gate (not shown) and the output signal of the seventh flip-flop F17, and performs the first bit of the second correction control signal S. (S1) is generated.

The output signal of the first flip-flop F11 is the thirteenth bit S13 of the second correction control signal S. The output signal of the second flip-flop F12 is the thirteenth bit C13 of the first correction control signal C. The output signal of the fourth flip-flop F14 is the twelfth bit C12 of the first correction control signal C. The output signal of the sixth flip-flop F16 is the eleventh bit C11 of the first correction control signal C. The output signal of the eighth flip-flop F18 is the first bit C1 of the first correction control signal C.

FIG. 14 is a block diagram illustrating a part of the correction coefficient extraction circuit 1330 included in the digital correction circuit 1300 of FIG. 8. The correction coefficient extraction circuit 1330 includes a plurality of correction coefficient extraction units 1330a shown in FIG. 14.

The correction coefficient extracting circuit 1330 of FIG. 8 includes a plurality of correction control signal generating circuits and a plurality of correction coefficient extracting units. Each of the plurality of correction control signal generation circuits performs a logic operation on each bit C1 to Cn of the first correction control signal C and each bit S1 to Sn of the second correction control signal S. The third correction control signal SC, the fourth correction control signal INRST, and the fifth correction control signal SUB are generated. Each of the plurality of correction coefficient extractors may include a first correction coefficient in response to the reference clock signal RCLK, the third correction control signal SC, the fourth correction control signal INRST, and the fifth correction control signal SUB. Generates one bit (ICn) of the IC).

Referring to FIG. 14, the correction coefficient extractor 1330a includes a first selection circuit 1331, a second selection circuit 1332, a first flip-flop array 1333, an adder 1334, and a third selection circuit 1335. ), A fourth selection circuit 1332, a second flip-flop array 1335, a first divider 1338, and a second divider 1335.

The first selection circuit 1331 selects and outputs one of the ground voltage and the second digital signal CDO in response to the reference clock signal RCLK. The second selection circuit 1332 selects and outputs one of an output signal of the first selection circuit 1331 and a ground voltage in response to the third correction control signal SC. The first flip-flop array 1333 delays the output signal of the second selection circuit 1332. The adder 1334 adds the first feedback signal to the output signal of the first flip-flop array 1333 and subtracts the fifth correction control signal SUB from the output signal of the first flip-flop array 1333. The first feedback signal is an output signal of the second flip-flop array 1335. The third selection circuit 1335 selects and outputs one of a ground voltage and an output signal of the adder 1334 in response to the fourth correction control signal INRST. The fourth selection circuit 1336 selects one of an output signal of the third selection circuit 1335 and a ground voltage in response to the third correction control signal SC. The second flip-flop array 1335 delays the output signal of the fourth selection circuit 1336 and outputs the first feedback signal. The first divider 1338 divides the first feedback signal at a division ratio of 1/2048. The second divider 1335 divides the output signal of the first divider 1338 at a dividing ratio of 1/2.

FIG. 15 is a circuit diagram illustrating a control signal generator for generating control signals in the correction coefficient extractor 1330a of FIG. 14. The correction coefficient extraction circuit 1330 of FIG. 8 includes a plurality of control signal generators shown in FIG. 15.

Referring to FIG. 15, the correction control signal generation circuit includes an OR gate OR11, a first inverter INV11, a second inverter INV12, a first AND gate AND11, and a second AND gate AND12. do.

The OR gate OR11 performs an OR operation on each bit Cn of the first correction control signal C and each bit Sn of the second correction control signal S, and performs a third correction control signal SC. Generates. The first inverter INV11 inverts each bit Cn of the first correction control signal. The second inverter INV12 inverts each bit Sn of the second correction control signal. The first AND gate AND11 performs an AND operation on each bit Sn of the output signal of the first inverter INV11 and the second correction control signal, and generates a fourth correction control signal INRST. The second AND gate AND12 performs an AND operation on each bit Cn of the output signal of the second inverter INV12 and the first correction control signal and generates a fifth correction control signal SUB.

FIG. 16 is a timing diagram illustrating an operation of the control signal generator illustrated in FIG. 15.
As shown in FIG. 16, Sn and Cn are generated in response to the reference clock signal RCLK. When the fifth correction control signal SUB is disabled, the adder 1334 of FIG. 14 operates in an adding mode. In contrast, when the fifth correction control signal SUB is enabled, the adder 1334 of FIG. 14 operates in a subtracting mode.

FIG. 17 is a block diagram illustrating a correction output circuit 1340 included in the digital correction circuit 1300 of FIG. 8.

Referring to FIG. 17, the correction output circuit 1340 includes flip-flops 1344, 1345, and 1346, adders 1341, 1342, and 1343, and flip-flop arrays 1347, 1348, and 1349.

The flip-flops 1344, 1345, and 1346 detect edges of the bits D1 to D13 of the first digital signal. The adders 1341, 1342, and 1343 are cascaded to each other, add the output signal of the previous stage to each of the plurality of first correction coefficients IC1 to IC13, and flip each of the plurality of first correction coefficients IC1 to IC13. The output signal of each of the flops 1344, 1345, and 1346 is subtracted and output. The flip-flop arrays 1347, 1348, and 1349 delay the output signals of the adders located at the end of the plurality of adders 1342, 1342, and 1343 in response to the clock signal CK and the inverted clock signal CKB, and perform a second correction. Output the coefficient (ICT).

FIG. 18 is a block diagram illustrating an adder 1360 included in the digital correction circuit 1300 of FIG. 8.

Referring to FIG. 18, the adder 1360 generates the second digital signal CDO by adding the second correction coefficient ICT to the third digital signal RDO.

19 is a timing diagram illustrating an operation of the digital correction circuit of FIG. 8.

Referring to FIG. 19, CFLAG activates correction logic, and stage 13 first enters correction mode. Stage 13 has four different modes defined by C13 and S13. In the reset mode, stage 13 is in stand-by mode and output D is set to zero. The correction mode consists of an addition mode and a subtraction mode in which an output signal is added or subtracted to obtain a correction coefficient IC13. In hold mode, the correction factor is stored in memory and reflected in the ADC output. There is a preset mode generated by RCLK at the beginning of the addition and subtraction modes. The function of the preset mode is to push away the incomplete input data to increase the accuracy of the data. After stage 13 enters the hold mode, stage 12 operates by control signals S12 and C12. This operation is repeated from stage 13 to stage 1. The ADC mode then changes from the extract / store mode to the read / modify mode.

20A and 20B are simulation diagrams of the pipelined analog-to-digital converter according to the embodiment of the present invention shown in FIG. 20A shows a waveform before digital correction, and FIG. 20B shows a waveform after digital correction.

20A and 20B, DNL represents differential non-linearity and INL represents integral non-linearity. The horizontal axis represents the number of bits that the ADC can represent, and the vertical axis represents nonlinearity.

As can be seen in Figures 20a and 20b, it can be seen that both the differential nonlinearity and the integral nonlinearity are improved after the correction.

As described above, the pipelined analog-to-digital converter according to the present invention has an automatic digital correction function because it has a digital correction circuit that can be embedded in the analog-to-digital converter. In addition, the pipelined analog-to-digital converter according to the present invention is excellent in linearity. In addition, since the pipeline analog-to-digital converter according to the present invention performs digital correction in response to one external flag signal, no setting of an additional signal is necessary.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (14)

A pipeline conversion circuit having a plurality of cascaded one-bit stages and converting an analog input signal into a first digital signal having a plurality of bits; And Extracting a correction coefficient for each bit of the first digital signal based on a correction control signal and a feedback converter output signal, and correcting the first digital signal in response to the correction coefficient to a second digital signal having a plurality of bits. Pipeline analog-to-digital converter comprising a digital correction circuit for generating a. delete The method of claim 1, wherein the digital correction circuit And generating said second digital signal in response to a flag signal. The method of claim 1, wherein the digital correction circuit A basic digital correction circuit for performing a basic correction on the first digital signal and generating a third digital signal; A correction control circuit for generating a reference clock signal, a first correction control signal having a plurality of bits, and a second correction control signal having a plurality of bits in response to the first clock signal and the first flag signal; A correction coefficient extraction circuit for extracting a plurality of first correction coefficients for the first digital signal in response to the reference clock signal, the first correction control signal, the second correction control signal, and a feedback signal; A correction output circuit for generating a second correction coefficient having a plurality of bits based on each bit of the first digital signal and the first correction coefficients; And And an adder for adding the second correction coefficient to the third digital signal to generate the second digital signal. The method of claim 4, wherein the correction control circuit A clock generator for dividing the first clock signal to generate a second clock signal, the reference clock signal, and a third clock signal; A flag generator for detecting the first flag signal and generating a second flag signal in response to the second clock signal, the reference clock signal, and the third clock signal; And And a correction control signal generator for generating the first correction control signal and the second correction control signal in response to the third clock signal and the second flag signal. 6. The apparatus of claim 5, wherein the clock generator A first clock divider for dividing the first clock signal at a first division rate to generate the second clock signal; A second clock divider for dividing the second clock signal at a second division rate to generate the reference clock signal; And And a third clock divider for dividing the reference clock signal at a third division rate to generate the third clock signal. The method of claim 6, Said first division rate being 1/64, said second division rate being 1/33, and said third division rate being 1/2. 6. The flag generator of claim 5, wherein the flag generator A first pulse detector detecting an edge of the first flag signal and generating a third flag signal in response to the second clock signal; A second pulse detector detecting an edge of the third flag signal and generating a fourth flag signal in response to the reference clock signal; And And a third pulse detector for detecting an edge of the fourth flag signal in response to the third clock signal and generating the second flag signal. The method of claim 5, wherein the correction control signal generator 2n th flip-flops operating in response to the third clock signal and 2n-1 (n> = 1 in response to a fourth clock signal in which the third clock signal is inverted Flip-flop circuits comprising a natural number) flip-flops; And An OR gate configured to perform an OR operation on the output signals of two immediately adjacent flip-flops among the 2n-1 th flip-flops and output the second correction control signal, And each bit of the first correction control signal is output from the output terminal of the 2n th flip-flop. The method of claim 4, wherein the correction coefficient extraction circuit A plurality of corrections for performing a logical operation on each bit of the first correction control signal and each bit of the second correction control signal and generating a third correction control signal, a fourth correction control signal, and a fifth correction control signal Control signal generation circuit; And And a plurality of correction coefficient extractors for generating one bit of the first correction coefficient in response to the reference clock signal, the third correction control signal, the fourth correction control signal, and the fifth correction control signal. Pipeline analog-to-digital converter. 12. The circuit of claim 10, wherein each of the correction control signal generation circuits An OR gate for performing an OR operation on each bit of the first correction control signal and each bit of the second correction control signal and generating the third correction control signal; A first inverter for inverting the first correction control signal; A second inverter for inverting the second correction control signal; A first AND gate configured to perform an AND operation on each bit of the output signal of the first inverter and the bit of the second correction control signal and generate the fourth correction control signal; And And a second AND gate for performing an AND operation on each bit of the output signal of the second inverter and each bit of the first correction control signal and generating the fifth correction control signal. converter. The method of claim 10, wherein each of the correction coefficient extraction units A first selection circuit configured to select one of a ground voltage and the second digital signal in response to the reference clock signal; A second selection circuit for selecting one of an output signal of the first selection circuit and the ground voltage in response to the third correction control signal; A first flip-flop array configured to delay an output signal of the second selection circuit; An adder for adding a first feedback signal to an output signal of the first flip-flop array and subtracting the fifth correction control signal from an output signal of the first flip-flop array; A third selection circuit for selecting and outputting one of a ground voltage and an output signal of the adder in response to the fourth correction control signal; A fourth selection circuit for selecting and outputting one of an output signal of the third selection circuit and the ground voltage in response to the third correction control signal; A second flip-flop array configured to delay an output signal of the fourth selection circuit and output the first feedback signal; A first divider which divides the first feedback signal at a first division rate; And And a second divider for dividing the output signal of the first divider at a second divider rate and generating one bit of the first correction factor. The method of claim 4, wherein the correction output circuit A plurality of flip-flops for detecting edges of respective bits of the first digital signal; A plurality of adders cascaded to each other and add an output signal of a previous stage to each of the plurality of first correction coefficients and subtract an output signal of each of the plurality of flip-flops from each of the plurality of first correction coefficients; And And a flip-flop array for delaying an output signal of an adder located at the end of the plurality of adders and outputting the second correction coefficient in response to a clock signal and an inverted clock signal. Performing basic correction on the first digital signal and generating a third digital signal; Generating a reference clock signal, a first correction control signal having a plurality of bits, and a second correction control signal having a plurality of bits in response to the first clock signal and the first flag signal; Extracting a plurality of first correction coefficients for the first digital signal in response to the reference clock signal, the first correction control signal, the second correction control signal, and a feedback signal; Generating a second correction coefficient having a plurality of bits based on each bit of the first digital signal and the first correction coefficients; And And generating the second digital signal by adding the second correction factor to the third digital signal.

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